Figure 7.

CPK2-PR, consisting of the GUS protein preceded by the first 10 amino acids of AtCPK2, is localized to the ER in transgenic Arabidopsis plants. Fractions from parallel Suc gradients, with and without Mg²⁺, were separated by SDS-PAGE and assayed by immunoblotting with antibodies specific for various membrane markers. AtCPK2-GUS fusion protein was assayed fluorimetrically. Horizontal bars indicate the peak fractions. ▴, +Mg²⁺ gradients; ●, −Mg²⁺gradients. The fraction with the highest activity was assigned a value of 100% that corresponds to 41.2 nmol min⁻¹ mL⁻¹ for the +Mg²⁺ gradients and 21.8 nmol min⁻¹ mL⁻¹ for the −Mg²⁺ gradients. Total GUS activity loaded onto the gradient was 146 nmol min⁻¹ for the +Mg²⁺ gradients and 199 nmol min⁻¹ for the −Mg²⁺ gradients.